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Math Help - graphs

  1. #1
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    graphs

    Suppose we have a graph of y = xsquared + 3x -2. What lines would you draw on it to solve the following eqautions?

    a) xsquared + 3x + 5 = 0
    b) xsquared + 4x -4 = 0
    c) xsquared -x - 1 = 0
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  2. #2
    Senior Member BAdhi's Avatar
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    a) x^2 + 3x -2 +7 =0
     x^2+3x -2 = -7

    y_{1} = x^2+3x-2
    y_{2} = -7

    when y_{1}=y_{2}
    you get the x value that satisfies the equation

    try others out in the same manner
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  3. #3
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    Hello, Natasha1!

    I'll do one of them . . .


    Suppose we have a graph of y \:=\: x^2 + 3x -2.
    What lines would you draw on it to solve the following eqautions?

    b)\;\;x^2 + 4x -4 \:=\: 0

    Draw the line y \:=\:-x + 2 . . . . why?


    To find the intersections of the parabola and the line,

    . . we have: . x^2+3x-2 \:=\:-x + 2 \quad\Rightarrow\quad x^2 + 4x - 4 \:=\:0


    The \,x-coordinates of the intersections are the roots of the quadratic equation.
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